Chain lubricant for conveyor and transport systems

ABSTRACT

The invention relates to a chain lubricant for conveyor and transport systems which is comprised of water, surfactants, disinfecting agents as well as conventional auxiliary agents and additives. According to the invention, an anionic surfactant is used as the surfactant and chlorine dioxide is used as the disinfecting agent.

The present invention concerns chain lubricants for conveyer andtransport systems, especially in the foodstuff industry, which aresuitable for lubrication, cleaning and disinfection of the transportchains. Furthermore, the invention concerns the process for the use ofthis chain lubricant.

The invention preferably concerns the lubrication of conveyoer andtransport chains in filling plant for foodstuffs, preferably of drinkswhich are filled into glass or synthetic material bottles, tins or otherdrink containers.

In the filling operation, the above containers are transported duringthe filling to various stations, for example cleaning stations, fillingstations, labelling stations, packing stations. This usually takes placeby means of conveying and transport plant which usually, for reasons ofhygiene and corrosion protection, consist of stainless steel but thetransport chain can also be of synthetic material. Such plant are, inthe following, designated as conveying plant.

In order to reduce mechanical stressing of containers and transportplant, a sufficient lubrication of the transport bands is necessary inorder that the band can be further moved unhindered even when thecontainers on the band can sometimes not be moved forwards.

If the conveying plant are not lubricated to a sufficient extent, thiscan, on the one hand, have the result that the containers fall over or,on the other hand, that they do not stop although the correspondingfilling, cleaning or labelling station is reached. Both kinds ofdisturbances can lead to comparatively long stationary times of theconveying plant and thus to considerable decreases of capacity. On theother hand, the lubrication is not to be so strong that the containers,already in the case of small counterforces, are no longer taken along bythe transport band, i.e. especially in the case of transfer from oneconveyor band to the other, in the case of ascending or descending bandsor in the case of insertion into the working stations are notsufficiently conveyed.

Besides the lubricating action, in the case of conveying plant in thefoodstuff industry, there is necessary especially also a cleaning anddisinfecting, especially biostatic action of the chain lubricant.

The chain lubricants at present used can be essentially divided into 3main groups:

1. lubricants based on soap,

2. lubricants based on fatty amines and

3. lubricants based on synthetic tensides.

The originally used lubrication based on soaps was usable relativelywithout problems and gave a good lubrication and cleaning but had thedisadvantage that the soap components represent a good nutrient mediumfor micro-organisms and, on the other hand, soaps are sensitive towardshard water so that complexing agents, for exampleethylenediamine-tetrascetic acid (EDTA) must additionally be added.Furthermore, EDTA can, in addition, only be broken down with difficultyin the clarification system.

For these reasons, today there are used especially lubricantconcentrates based on fatty amines, as well as amphoteric tensides (e.g.alkylaminoalkylcarboxylic acids (cf. DE 36 31 953-A1 and WO95/33808-A1). Since these amino compounds themselves display only asmall biocidal and cleaning action, in DE 36 31 953-A1 it is recommendedadditionally to clean and disinfect at regular intervals the plant withan acidic cleaning fluid which requires a considerable expense.

Furthermore, from WO 96/02616-A1 are known chain lubricants whichconsist of alkylpolyglycol phosphoric acid esters to which areadditionally added aromatic biocides or quaternary ammonium compounds.

From EP 0 044 458-A1 and DE 196 42 598-A1 are known chain lubricantsbased on alkylpolyglycol-carboxylic acids which, alone or in admixturewith other tensides, display a good lubricating and purifying action, incomparatively high concentration these products even appear to display acertain biocidal action although it is stated in DE 196 42 598-A1 thatthe products can be broken down not only aerobically but alsoanaerobically in clarification plant.

Furthermore, from EP 0 359 145-A1 are known soap-free lubricantcompositions which contain alkylbenzene-sulphonates, alkoxylated alkanolphosphates and alkane-carboxylic acids, as well as usual adjuvants andto which, as disinfecting agents, are added glutaraldehyde,isothiazoline, oxy compounds or pyridinethiol oxide in 5-50% of thetensides.

The use of quaternary ammonium compounds as disinfecting agents incleaning agents with which normally conveyor systems lubricated withfatty amines are from time to time cleaned is described in DE 36 31953-A1. On the other hand, in DE 39 05 548-A1 it is attempted, by use ofsecondary and/or tertiary amines, to use lubricants which show their ownbiocidal action. Although these products are to show their own cleaningaction, it is, nevertheless, recommended to carry out an additionalcleaning from time to time with organic or inorganic acids.

It is common to all of the above proposals that, insofar as a biocidalcomponent is contained in the mixture this finally gets into waste waterand, especially when they occur in comparatively high concentrations,can disturb the aerobic and anaerobic biological stages in clarificationplant.

Therefore, the task arises to develop chain lubricants which are notbased on cationic or amphoteric tensides. The biocidal components of thechain lubricants must be those which safely and quickly kill of germsdamaging the filling materials but, on the other hand, can readily bebroken down biologically and must not negatively influence clarificationplant and the environment. The solution was, surprisingly, found in theuse of anionic tensides with chlorine dioxide as disinfection agent insuch chain lubricants.

Surprisingly, it was ascertained that chlorine dioxide in the necessarylow concentrations clearly increases the partly known lubricant actionof the tensides contained so that their concentration can be lowered,which represents a further relief of the environment.

It is known that chlorine dioxide is suitable for the bleaching in thetextile, cellulose and paper industry, as well as also for waterdisinfection, disinfection and deodorising of evil-smelling wastes andwaste water, as well as for the bleaching of oils, fats and waxes (cf.RÖMPPS Chemie-Lexikon, 9th edition, p. 711). Corresponding aqueoussolutions are, therefore, produced and used on a large scale. However,these are not stable and have an unpleasant pungent smell from thechlorine dioxide gassing off which acts irritatingly on the respiratorycanal and, therefore, is usually only handled in closed vessels.

Surprisingly, it has now been found that the concentration of chlorinedioxide in the chain lubricant necessary for an antimicrobial action isso small that a noticeable gassing off does not take place. On the otherband, it appears to be surprising that the low concentrations ofchlorine dioxide are not reduced and thus inactivated by the othercomponent materials of the chain lubricants which, in comparisonthereto, are present in considerable excess, especially by the tensidesused. An influencing of the clarification plant can be excluded sincethese small amounts of chlorine dioxide are so rapidly reduced by othereasily oxidisable materials occurring in the waste water that theaerobic and anaerobic biological steps of the clarification plant arenot disturbed. Since, due to this reduction, practically only chlorideions still remain, this type of disinfection, in contradistinction tothe biocides and biocidally-acting tensides used according to the priorart, do not influence the environment.

For a sufficient disinfection of transport chains, it suffices when thechain lubricants contain chlorine dioxide in very small concentration. Aconcentration of 0.5-5 mg/l, especially of about 1-3 mg/l, has proved tobe especially useful. First above 5 mg/l is a weak smell of chlorinedioxide noticeable which, above 10 mg/l, becomes unpleasantly clear. Acompletely sufficient disinfection of the transport chains is ensuredwhen the transport chain is, in the case of each cycle, again contactedwith the chain lubricant which, in the case of usual transport speeds(0.5-3)m/sec in the case of 40 m length) takes place in about every 0.5to 3 min. For this purpose, the chain can either run through anappropriate bath of chain lubricant or is preferably sprayed with thechain lubricant, whereby a thin film of the chain lubricant fixes on thechain.

The aqueous chain lubricant contains tensides and adjuvants in amountsof 0.2-1.5 g/l, preferably of 0.3-1.0 g/l, as aqueous solution by meansof which the necessary lubricating action is achieved. As tensides,there are especially preferred monoalkyl-polyalkylene glycol ethercarboxylic acids of the following general formula (I):

R₁—(OC₂H₄)_(m)—(OC₃H₆)_(n)—O—(CH₂)_(p)—CHR₂—C(O)OR₃  (I)

wherein R₁ signifies a saturated linear or branched C₁-C₂₂ alkylradical, a mono- or polyunsaturated linear or branched alkenyl oralkynyl radical with 2 to 22 carbon atoms or an aryl radical possiblysubstituted one or more times by C₁-C₂₂-alkyl or alkenyl or alkynylgroups,

m a number in the range of 0 to 30,

n a number in the range of 0 to 30,

p a number in the range of 1 to 4,

R₂ a hydroxyl group or a hydrogen and

R₃ hydrogen, a methyl group or an alkali metal.

Furthermore, as tensides, there are especially preferredalkylbenzene-sulphonic acids and their salts of the following generalformula (II):

 R₄—C₆H₆—SO₃M  (II)

wherein R₄ signifies a saturated linear or branched C₁-C₂₂-alkyl radicalor a mono- or polyunsaturated linear or branched alkenyl or alkynylradical with 2 to 22 carbon atoms and M is hydrogen or an alkali metal.

Further especially preferred are monoalkyl-poly-alkylene glycolphosphoric acid mono- or diesters of the following general formula(III);

(R₅—(OC₂H₄)_(q)—OC₃H₆)_(r)—O)_(s)—PO₂R₆H  (III)

wherein R₅ signifies a saturated linear or branched C₁-C₂₂-alkylradical, a mono- or polyunsaturated alkenyl or alkynyl radical with 2 to22 carbon atoms or an aryl radical possibly mono- or poly-substituted byC₁-C₂₂-alkyl or alkenyl or alkynyl groups,

q is a number in the range of 0 to 30,

r a number in the range of 0 to 30,

s 1 or 2,

R₆ is a hydroxyl group insofar as s is 1 and

R₆ is omitted insofar as s is 2.

Furthermore, other anionic and nonionic tensides can be added to themixture. Fatty amines, other cationic tensides and amphoteric tensidesare expressly not component of the invention since, in usually usedconcentration, they can exert a damaging influence on clarificationplant.

As adjuvants, there are especially usual polyethylene glycols via whichthe viscosity of the solution and the tolerance against hard water canbe improved. Amounts of 0.5-5 g/l are thereby usable. As solubiliser,there can, furthermore, be used alcohols or ethers, such as isopropanol,butyl glycol, dibutyl glycol or ethylene glycol ether. Furthermore, tothe mixture can be added acids or bases for the regulation of the pHvalue which is preferably to lie in a range of 5 to 8.

For economic reasons, it is useful to produce the chain lubricant asconcentrate and first to dilute to the above concentration for use,whereby, at the same time, the disinfecting chlorine dioxide is added asaqueous solution. The concentrates usually have concentrations of about2-30 wt. % of component materials and 98-70 wt. % of water so that thedesired end concentration can be adjusted by addition of the 100 to 1000fold amount of water.

The concentration of the chain lubricant in the solutions used must beso adjusted that they clearly reduce the frictional resistance betweenconveyed goods and transport chain. The frictional resistance is definedby the so-called frictional value. Solutions of use of chain lubricantsmust display a frictional value in the range of 0.1-0.2, preferably0.11-0.15. The frictional value is determined in that one places flaskson a transport band which is continuously sprayed with the lubricantsolution and moved with constant speed. One measures the pressure whichthe flasks exert in the direction of transportation on a firmly standingobstacle. The frictional value is then given as quotient from themeasured pressure and the weight of the flask in g.

For pure water as control, there are given frictional values of 0.45 to0.5, for water mixed with 0.1-3.0% commercially available chainlubricant frictional values of 0.1 to 0.25.

Experiments with differing tensides and differing amounts of chlorinedioxide are given in the following table. The differing tensides werethereby dissolved in amounts of 1-4 g/10 l of water and 0.55 mg/l, 1.36mg/l, 5.45 mg/l or 8.17 mg/l chlorine dioxide added thereto. The pHvalue of the solution lay at about 7.5+/−0.5. For comparison, a fewcommercially available products are also given which are used in eachcase in the concentrations of 3 or 5 g/l usually used. The followingabbreviations of the raw materials are used:

T1: C₁₆-C₁₈-ether carboxylic acid with one ethylene oxide group

T2: C₁₆-C₁₈-ether carboxylic acid with 2 ethylene oxide groups

T3: C₁₆-C₁₈ether carboxylic acid with on average 5 ethylene oxide groups

T4: linear alkyl(C₁₀₋₁₃)-benzene-sulphonic acid

T5: alkyl(C₁₂₋₁₈)-ethoxy(6-20 EO)-propoxy (less than 8 PO)-phospboricacid mono- and diesters

H₁: commercial product based on amphotensides

H₂: commercial product based on amino and acetic acid

H₃: commercial product based on fatty amino and acetic acid

H₄: commercial product based on amino and lactic acid

H₅: commercial product based on alkali metal fatty acid salts (soaps).

TABLE 1 ClO₂ mg/l 0.55 0.0 mg/l mg/l 1.36 mg/l 5.45 mg/l 8.17 mg/l smellnone none none weak distinct raw g/10 1 frictional value (fv) materialbatch T1 1 0.236 0.192 0.333 0.365 T1 2 0.164 0.162 0.236 0.233 T1 40.197 0.165 0.134 0.136 0.140 T2 4 0.194 0.174 T3 4 0.271 0.135 T4 40.297 0.194 T5 4 0.194 0.20 mixtures of tensides T1/T4 2/2 0.151 0.1330.129 T2/T4 2/2 0.252 0.165 T3/T4 2/2 0.234 0.196 T1/T5 2/2 0.123 0.1280.122 T2/T5 2/2 0.143 0.122 T3/T5 2/2 0.211 0.183 commercially availablechain lubricants H₁ 30  0.280 0.365 H₂ 30  0.138 0.136 0.140 H₃ 30 0.142 0.149 H₄ 30  0.135 0.450 H₅ 50  0.281 0.397

In a further experiment, the germ-killing action was investigated on thebasis of micro-organisms frequently occurring in the range of fillingplant. For this purpose, a solution of 4 g ether carboxylic acid T1 wasmixed with 0.1-0.5 mg ClO₂/l and in each case 90 ml of a so preparedsolution mixed with 10 ml of bacteria solution which bad a concentrationof about 10,000 cells/ml so that in all there was given a concentrationof 1000 cells/ml which corresponds to usual concentrations in therinsing water. At the times given in the Tables, samples were withdrawnand the decrease of the cell count investigated by means of dilutionseries and living titre plating out (revolving table, Drigalskyspatula). The following Tables show that bacteria already atconcentrations of 0.3 mg/ml are killed off with certainty within 5 min.Yeast cells at this concentration are clearly damaged and at 0.5 mg/lare also completely killed off.

TABLE 2 Concentration 0.1 mg ClO₂/l contact time Organism 0 min 5 min 10min 20 min 30 min E. coli 2050.00 1450.00  1030.00  1040.00  1010.00 yeast 900.00 910.00 870.00 910.00 890.00 Pectinatus 1020.00 — — — —lactic acid 1230.00 420.00 150.00 110.00 110.00 bacteria Pediococci1020.00 100.00  12.00 — —

TABLE 3 Concentration 0.15 mg ClO₂/l contact time organism 0 min 5 min10 min 20 min 30 min E. coli 1000.00 — — — — yeast 1050.00 100.00 — — —Pectinatus 1820.00 — — — — lactic acid 1710.00 — — — — bacteriaPediococci 570.00 400.00 60.00

TABLE 4 Concentration 0.3 mg ClO₂/l contact time organism 0 min 5 min 10min 20 min 30 min E. coli 1150.00 — — — — yeast 950.00 90.00 — — —Pectinatus 920.00 — — — — lactic acid 1200.00 — — — — bacteriaPediococci 900.00 — — — —

TABLE 5 Concentration 0.5 mg ClO₂/l contact time organism 0 min 5 min 10min 20 min 30 min E. coli 1050.00 — — — — yeast 900.00 — — — —Pectinatus 960.00 — — — — lactic acid 1200.00 — — — — bacteriaPediococci 1000.00 — — — —

Especially in the presence of organic substance, chlorine dioxidedecomposes to ineffective compounds, such as chlorides.

Therefore, in the preliminary experiment, the breakdown speed ofchlorine dioxide in the open stirred system was determined in order tosimulate as far as possible the conditions of a transport chain. Forthis purpose, in a 2 litre glass beaker was again prepared a solution of4 g/10 l T1 and mixed with 5, 3 or 1 mg/l chlorine dioxide. In eachcase, 100 ml of this solution were filled into the glass beaker andstirred for 4 hours with a rapidly running winged stirrer. The chlorinedioxide content is measured with a selective electrode. The measurementresults are given in the following Table.

TABLE 6 Breakdown speed of chlorine dioxide starting concen- time(minutes) tration ClO₂ mg/l 30 60 120 180 240 5 3.8 3.5 3.1 2.8 2.4 32.5 2.1 1.5 1 0.5 1 0.8 0.6 0.5 0.3 0.2

Also even after four hours, there is given a decrease of theconcentration to still effective concentrations.

What is claimed is:
 1. Chain lubricant for conveyor and transportsystems comprising water, a tenside selected from the group consistingof a) a tenside comprising a monoalkyl-polyalkyleneglycol ethercarboxylic acid of the following formula (I)R₁—(OC₂H₄)_(m)—(OC₃H₆)_(n)—O—(CH₂)_(p)—CHR₂—C(O)OR₃  (I) wherein R₁signifies a saturated linear or branched C₁-C₂₂-alkyl radical, a mono-or polyunsaturated linear or branched alkenyl or alkynyl radical with 2to 22 carbon atoms or an aryl radical optionally substituted one or moretimes by C₁-C₂₂-alkyl or alkenyl or alkynyl groups, m is a number in therange of 0 to 30, n is a number in the range of 0 to 30, p is a numberin the range of 1 to 4, R₂ is a hydroxyl group or a hydrogen and R₃ ishydrogen, a methyl group or an alkali metal; b) a tenside comprising analkyl-benzenesulphonic acid or one of its salts of the following generalformula (II) R₄—C₆H₆—SO₃M  (II) wherein R4 is a saturated linear orbranched C₁-C₂₂-alkyl radical or a mono- or poly-unsaturated linear orbranched alkenyl or alkynyl radical with 2 to 22 carbon atoms and M ishydrogen or an alkali metal; c) a tenside comprising amonoalkyl-polyalkyleneglycol phosphoric acid mono or diester of thegeneral formula (III) (R₅—(OC₂H₄)_(q)—(OC₃H₆)_(r)—O)_(s)—PO₂R₆H  (III)wherein R₅ signifies a saturated linear or branched C₁-C₂₂-alkylradical, a mono- or polyunsaturated linear or branched alkenyl oralkynyl radical with 2 to 22 carbon atoms or an aryl radical optionallysubstituted one or more times by C₁-C₂₂-alkyl or alkenyl or alkynylgroups, q is a number in the range of 0 to 30, r is a number in therange of 0 to 30, s is 1 or 2, R₆ is hydroxyl if s is 1 and, if s is 2,R₆ is not present; and d) mixtures thereof; and disinfection agents, aswell as adjuvant and additive materials, wherein said disinfection agentcomprises chlorine dioxide.
 2. A chain lubricant according to claim 1,wherein said chain lubricant comprises anionic and nonionic tensides,additives and adjuvants.
 3. A chain lubricant according to claim 1,wherein said chain lubricant comprises the chlorine dioxide in aconcentration of 0.5-5 mg/l and the tensides in a concentration of 0.1-1g/l.
 4. Process for the lubrication of chains of conveyor and transportbands, comprising mixing together a chain lubricant according to claim1, said chain lubricant comprising a concentrate of the tensides,additive and adjuvant materials and a solution of chlorine dioxide andan amount of water sufficient to obtain a desired concentration andapplying the resulting mixture to a transport chain continuously or atintervals.
 5. A process according to claim 4, comprising contacting eachposition of said transport chain, during circulation, with fresh chainlubricant at time intervals of 0.5-3 minutes.
 6. A chain lubricant forconveyor and transport systems comprising water, a tenside selected fromthe group consisting of a) a tenside comprising amonoalkyl-polyalkyleneglycol ether carboxylic acid of the followingformula (I) R₁—(OC₂H₄)_(m)—(OC₃H₆)_(n)—O—(CH₂)_(p)—CHR₂—C(O)OR₃  (I)wherein R₁ signifies a saturated linear or branched C₁-C₂₂-alkylradical, a mono- or polyunsaturated linear or branched alkenyl oralkynyl radical with 2 to 22 carbon atoms or an aryl radical optionallysubstituted one or more times by C₁-C₂₂-alkyl or alkenyl or alkynylgroups, m is a number in the range of 0 to 30, n is a number in therange of 0 to 30, p is a number in the range of 1 to 4, R₂ is a hydroxylgroup or a hydrogen and R₃ is hydrogen, a methyl group or an alkalimetal; b) a tenside comprising an alkyl-benzenesulphonic acid or one ofits salts of the following general formula (II) R₄—C₆H₆—SO₃M  (II)wherein R4 is a saturated linear or branched C₁-C₂₂-alkyl radical or amono- or poly-unsaturated linear or branched alkenyl or alkynyl radicalwith 2 to 22 carbon atoms and M is hydrogen or an alkali metal; c) atenside comprising a monoalkyl-polyalkyleneglycol phosphoric acid monoor diester of the general formula (III)(R₅—(OC₂H₄)_(q)—(OC₃H₆)_(r)—O)_(s)—PO₂R₆H  (III) wherein R₅ signifies asaturated linear or branched C₁-C₂₂-alkyl radical, a mono- orpolyunsaturated linear or branched alkenyl or alkynyl radical with 2 to22 carbon atoms or an aryl radical optionally substituted one or moretimes by C₁-C₂₂-alkyl or alkenyl or alkynyl groups, q is a number in therange of 0 to 30, r is a number in the range of 0 to 30, s is 1 or 2, R₆is hydroxyl if s is 1 and, if s is 2, R₆ is not present; and d) mixturesthereof; and disinfection agents, as well as adjuvant and additivematerials, said disinfection agent comprises chlorine dioxide andwherein said lubricant is free of cationic tensides and fatty aminecompounds.
 7. A chain lubricant for conveyor and transport systemscomprising water, a tenside selected from the group consisting of a) atenside comprising a monoalkyl-polyalkyleneglycol ether carboxylic acidof the following formula (I)R₁—(OC₂H₄)_(m)—(OC₃H₆)_(n)—O—(CH₂)_(p)—CHR₂—C(O)OR₃  (I) wherein R₁signifies a saturated linear or branched C₁-C₂₂-alkyl radical, a mono-or polyunsaturated linear or branched alkenyl or alkynyl radical with 2to 22 carbon atoms or an aryl radical optionally substituted one or moretimes by C₁ —C₂₂-alkyl or alkenyl or alkynyl groups, m is a number inthe range of 0 to 30, n is a number in the range of 0 to 30, p is anumber in the range of 1 to 4, R₂ is a hydroxyl group or a hydrogen andR₃ is hydrogen, a methyl group or an alkali metal; b) a tensidecomprising an alkyl-benzenesulphonic acid or one of its salts of thefollowing general formula (II) R₄—C₆H₆—SO₃M  (II) wherein R4 is asaturated linear or branched C₁-C₂₂-alkyl radical or a mono- orpoly-unsaturated linear or branched alkenyl or alkynyl radical with 2 to22 carbon atoms and M is hydrogen or an alkali metal; c) a tensidecomprising a monoalkyl-polyalkyleneglycol phosphoric acid mono ordiester of the general formula (III)(R₅—(OC₂H₄)_(q)—(OC₃H₆)_(r)—O)_(s)—PO₂R₆H  (III) wherein R₅ signifies asaturated linear or branched C₁-C₂₂-alkyl radical, a mono- orpolyunsaturated linear or branched alkenyl or alkynyl radical with 2 to22 carbon atoms or an aryl radical optionally substituted one or moretimes by C₁-C₂₂-alkyl or alkenyl or alkynyl groups, q is a number in therange of 0 to 30, r is a number in the range of 0 to 30, s is 1 or 2, R₆is hydroxyl if s is 1 and, if s is 2, R₆ is not present; and d) mixturesthereof; and disinfection agents, as well as adjuvant and additivematerials, wherein said disinfection agent comprises chlorine dioxide ina concentration of 0.5 to 5 mg/l.